By AGENCE FRANCE PRESSE, Aleppo, Syrian Arab Republic, Sep 20 – Air raids and shelling pounded key battlefronts in Syria on Tuesday, as outrage mounted over a strike on an aid convoy hours after Syria’s military declared an end to a week-long truce.

The raid and renewed violence across the country dimmed hopes that the fraught ceasefire negotiated by Moscow and Washington could be revived.

Key players including the United States and Russia were to meet in New York Tuesday in an effort to salvage the peace process, which US Secretary of State John Kerry had warned could be the “last chance” to end Syria’s civil war.

But on the ground in Syria, activists and AFP correspondents reported intensifying fighting.

In the battleground city of Aleppo, air raids and artillery fire hit rebel-held districts until approximately 2:00 am (2300 GMT Monday), an AFP correspondent said.

At least 39 civilians were killed in overnight bombardment of Aleppo and the surrounding province, the Syrian Observatory for Human Rights monitoring group said, and fresh clashes had erupted on the southern edges of the city.

In the week after the truce was declared on September 12, only 27 civilians were killed as fighting dropped significantly across the country.

Those killed overnight included 12 people, mostly humanitarian workers, who died on a raid on a joint United Nations, Red Cross, and Red Crescent convoy delivering assistance to the town of Orum al-Kubra in Aleppo province.

– UN ‘war crime’ warning –

An infuriated United Nations warned Monday night’s attack, which destroyed at least 18 trucks in the 31-vehicle convoy, could amount to a war crime.

“Let me be clear: if this callous attack is found to be a deliberate targeting of humanitarians, it would amount to a war crime,” aid chief Stephen O’Brien said.

“Our outrage at this attack is enormous,” the UN envoy for Syria, Staffan de Mistura, told reporters.

“The convoy was the outcome of a long process of permission and preparations to assist isolated civilians.”

An AFP correspondent at the scene of the strike early Tuesday saw damaged boxes of medical supplies and bags of aid spilling out of charred green trucks.

“Considering that the conditions of the ceasefire are not being respected by the rebels, we consider it pointless for the Syrian government forces to respect it unilaterally,” said Russian Lieutenant General Sergei Rudskoy.

The truce had already come under massive strain when a US-led coalition strike on Saturday hit a Syrian army post near the eastern city of Deir Ezzor, where government forces are battling the Islamic State jihadist group

Syrian President Bashar al-Assad on Monday blasted the strike, which killed dozens of troops, as “flagrant American aggression”.